When to plant radishes in California
California’s average last spring frost is February 20, and the first fall frost typically arrives around December 1 — about 284 frost-free days (USDA zones 5a, 6b, 7b, 8b, 9b, 10a, 10b). Radish needs 22–30 days to mature, which fits comfortably within California's growing season.
California covers a wide range of climates, so your exact frost dates may differ from the state average by two weeks or more. For dates tuned to your town, use the calendar generator.
When to plant radishes in California: the short answer
For a spring planting, sow Jan 18 – Feb 6. Seeds germinate in soil from 40 to 85°F.
Succession sow again in California: Feb 2 · Feb 12 · Feb 22 · Mar 4 · Mar 14 · Mar 24
Spring succession stops before summer heat makes it bolt. Start sowing again in late summer for a fall crop (see the fall window above).
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow radishes in California, step by step
- Prepare the bed. They need six or more hours of sun for the best growth, though four to six hours in partial shade is enough and loose soil at least 6 inches deep, with a pH between 6.0 and 7.0. Dig in compost before planting.
- Sow outdoors (Jan 18 – Feb 6). Space plants about 2 inches apart in rows 6 inches apart, sowing seed ½ inch deep. It handles frost well, so it can go out before the last frost date. As a cool-season crop it does best before summer heat arrives in California.
- Water and feed. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: flea beetle, cabbage root maggot, aphids. Diseases and disorders: clubroot, scab, downy mildew.
- Harvest (from about Feb 14 – Feb 22). Radish takes 22-30 days to reach harvest. The classic marker crop and quick filler. Sow a short row every 10 days - a single big sowing all matures at once and then goes pithy and hot.
Figures come from our crop data; dates use California’s average frost dates. More in the full radish growing guide.
Radish planting dates by USDA zone in California
California spans USDA zones 5a, 6b, 7b, 8b, 9b, 10a, 10b. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average, so the radish dates shift with them.
| Zone | Last frost | First frost | Season | Start indoors | Plant radish |
|---|---|---|---|---|---|
| Zone 5 | Apr 30 | Oct 5 | 160 days | - | Mar 28 – Apr 16 |
| Zone 6 | Apr 15 | Oct 15 | 185 days | - | Mar 13 – Apr 1 |
| Zone 7 | Apr 5 | Oct 25 | 200 days | - | Mar 3 – Mar 22 |
| Zone 8 | Mar 20 | Nov 5 | 230 days | - | Feb 15 – Mar 6 |
| Zone 9 | Feb 20 | Nov 30 | 280 days | - | Jan 18 – Feb 6 |
| Zone 10 | Jan 30 | Dec 15 | 330 days | - | Dec 28 – Jan 16 |
Questions gardeners in California ask
When is the best time to plant radishes in California?
Sow radishes in California between January 18 and February 6. That timing is set by California's average last spring frost of February 20; California spans several climates, so cooler and higher parts of the state run later.
Can I plant radishes in the fall in California?
Yes. For a fall crop, sow between October 17 and November 3, so the crop matures in cool weather before California's first frost around December 1.
When will radishes planted in California be ready to harvest?
Planted on time, radishes are usually ready from about February 14 to February 22, 22-30 days after sowing.
When is the last frost in California?
On average around February 20, with the first fall frost around December 1 - about 284 frost-free days. Your town may differ by two weeks or more.